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Environmental fate & pathways

Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Study period:
10 September 2012 to 22 November 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
The analogue approach is used for the hazard assessment of toxicological endpoints for the registration of the target substance pentaerythritol ricinoleate (CAS 78-22-8) based on generation of different breakdown/metabolic products, resulting not only in similar physical and biological systems (Scenario 2 of the Read-Across Assessment Framework (RAAF, ECHA, 2015), but also consequently in similar physico-chemical, environmental fate and ecotoxicological properties. The source compound for read-across is fatty acids, C16-18 and C18 unsatd., esters with pentaerythritol (CAS 85116-93-4). It is proposed that the different alcohols resulting from ester hydrolysis of the source compound and the target substance will not result in significant variation in biological effects. Neither target nor source compounds are classified for hazardous effects based on aquatic toxicity. The use of reliable experimental data, all evaluated as reliable according to Klimisch scores of 1 or 2, to estimate the environmental fate and ecotoxicity of the registered substance is adequate for the purposes of fulfilling the data requirements of registration and classifying potential hazards. Similar grouping into categories has been accepted by other regulatory agencies (U.S. EPA, 2010; U.S. FDA for food notifications). Thus, this read-across approach is adequate for the purposes of risk assessment and classification and labeling.


Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
adopted 17 July 1992 "Ready Biodegradability-CO2 Evolution (Modified Sturm Test)"
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Version / remarks:
No. 440/2008, Method C.4-C, adopted 31 May 2008, "Determination of Ready Biodegradability - Carbon Dioxide (CO2) Evolution (Modified Sturm Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
The test substance is listed as Fatty acids, C16-18 and C18-unsatd., esters with pentaerythritol. The test substance is a yellow to amber colored liquid. The test substance was obtained from the Sponsor, Oleon NV and stored in a tightly closed vessel at room temperature in dry conditions.
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
Activated sludge from a biologic sewage treatment plant treating mostly domestic sewage was used. The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf on 19 October 2012. The sludge was filtered, washed with tap water twice, then washed with and resuspended in test medium. It was then aerated for > 12 hours.
Duration of test (contact time):
28 d
Initial conc.:
27.1 mg/L
Based on:
test mat.
Initial conc.:
20.2 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
The test item, at a concentration of 20 mg carbon/L(corresponding to 26.8 mg test item/L), was exposed to activated sewage sludge micro-organisms with mineral medium in sealed culture vessels in the dark at measured temperatures of between 17.1 and 21.5 °C for 29 days. The biodegradation of the test item was assessed by the determination of carbon dioxide produced. Control solutions with inoculum and the reference item, aniline, together with a toxicity control were used for validation purposes.
Reference substance:
aniline
Key result
Parameter:
% degradation (CO2 evolution)
Value:
69
Sampling time:
29 d
Details on results:
The test item attained 69% biodegradation after 29 days. At the 10-day window, the test item reached 55% biodegradation Under the strict terms and conditions of OECD Guideline No. 301B the test item cannot be considered to be readily biodegradable as the test item failed to satisfy the 10-day window validation criterion, whereby 60% biodegradation must be attained within 10 days of the biodegradation exceeding 10%. However, the test item is a UVCB and has exhibited the potential for rapid biodegradation.
Results with reference substance:
Degradation of the positive control was 62% after eleven days.
Validity criteria fulfilled:
yes
Remarks:
IC content <1% (protocol ≤ 5%); CO2 emitted by controls 14.0 mg/L (protocol <70 mg/L; difference replicates 14.5% (protocol ≤20 %); degradation positive control >60% at 11 d (protocol ≤14 d), degradation toxicity d 14, 61% (protocol > 25%).
Interpretation of results:
readily biodegradable, but failing 10-day window
Conclusions:
The test item attained 69% biodegradation after 29 days. Under the strict terms and conditions of OECD Guideline No. 301B the test item cannot be considered to be readily biodegradable as the test item failed to satisfy the 10-day window validation criterion, whereby 60% biodegradation must be attained within 10 days of the biodegradation exceeding 10%. However, the test item is a UVCB and has exhibited the potential for rapid biodegradation.
Endpoint:
biodegradation in water: screening test, other
Type of information:
(Q)SAR
Remarks:
(Q)SAR BIOWINv4.10
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
Modeling report of BIOWIN v4.10, a model contained within EPI-Suite version 4.1, a reliable QSAR model.
Qualifier:
no guideline followed
Principles of method if other than guideline:
BIOWIN v4.10 a model with U.S. EPA's EPI-Suite, a reliable QSAR model included in the OECD QSAR Toolbox.
GLP compliance:
no
Remarks:
Not applicable.
Parameter followed for biodegradation estimation:
other: (Q)SAR Model biodedgradation prediction
Key result
Parameter:
probability of ready biodegradability (QSAR/QSPR)
Value:
> 0.5
Sampling time:
28 d
Remarks on result:
readily biodegradable based on QSAR/QSPR prediction
Remarks:
BIOWIN5 Prediction (MITI linear Biodeg. Probability = 1.3308)

BIOWIN (v4.10) Program Results:

==============================

SMILES : O=C(OCC(CO)(CO)CO)CCCCCCCC=CCC(O)CCCCCC

CHEM  : 9-Octadecenoic acid, 12-hydroxy-, 3-hydroxy-2,2-bis(hydroxymethyl)propyl ester, R-(Z) -

MOL FOR: C23 H44 O6

MOL WT : 416.60

--------------------------- BIOWIN v4.10 Results ----------------------------

 

  Biowin1 (Linear Model Prediction)   : Biodegrades Fast

  Biowin2 (Non-Linear Model Prediction): Biodegrades Fast

  Biowin3 (Ultimate Biodegradation Timeframe): Weeks

  Biowin4 (Primary Biodegradation Timeframe): Days

  Biowin5 (MITI Linear Model Prediction)   : Biodegrades Fast

  Biowin6 (MITI Non-Linear Model Prediction): Biodegrades Fast

  Biowin7 (Anaerobic Model Prediction): Biodegrades Fast

  Ready Biodegradability Prediction: YES

 

------+-----+--------------------------------------------+---------+---------

 TYPE | NUM |      Biowin1 FRAGMENT DESCRIPTION        | COEFF | VALUE 

------+-----+--------------------------------------------+---------+---------

 Frag | 1 | Linear C4 terminal chain [CCC-CH3]      | 0.1084 | 0.1084

 Frag | 4 | Aliphatic alcohol [-OH]                 | 0.1587 | 0.6349

 Frag | 1 | Ester  [-C(=O)-O-C]                     | 0.1742 | 0.1742

 Frag | 1 | Carbon with 4 single bonds & no hydrogens | -0.1839 | -0.1839

 MolWt| * | Molecular Weight Parameter               |        | -0.1983

 Const| * | Equation Constant                        |        | 0.7475

============+============================================+=========+=========

  RESULT  |   Biowin1 (Linear Biodeg Probability)    |        | 1.2828

============+============================================+=========+=========

 

------+-----+--------------------------------------------+---------+---------

 TYPE | NUM |      Biowin2 FRAGMENT DESCRIPTION        | COEFF | VALUE 

------+-----+--------------------------------------------+---------+---------

 Frag | 1 | Linear C4 terminal chain [CCC-CH3]      | 1.8437 | 1.8437

 Frag | 4 | Aliphatic alcohol [-OH]                 | 1.1178 | 4.4712

 Frag | 1 | Ester  [-C(=O)-O-C]                     | 4.0795 | 4.0795

 Frag | 1 | Carbon with 4 single bonds & no hydrogens | -1.7232 | -1.7232

 MolWt| * | Molecular Weight Parameter               |        | -5.9158

============+============================================+=========+=========

  RESULT  | Biowin2 (Non-Linear Biodeg Probability)  |        | 0.9969

============+============================================+=========+=========

 

 A Probability Greater Than or Equal to 0.5 indicates --> Biodegrades Fast

 A Probability Less Than 0.5 indicates --> Does NOT Biodegrade Fast

 

------+-----+--------------------------------------------+---------+---------

 TYPE | NUM |      Biowin3 FRAGMENT DESCRIPTION        | COEFF | VALUE 

------+-----+--------------------------------------------+---------+---------

 Frag | 1 | Linear C4 terminal chain [CCC-CH3]      | 0.2983 | 0.2983

 Frag | 4 | Aliphatic alcohol [-OH]                 | 0.1600 | 0.6399

 Frag | 1 | Ester  [-C(=O)-O-C]                     | 0.1402 | 0.1402

 Frag | 1 | Carbon with 4 single bonds & no hydrogens | -0.2121 | -0.2121

 MolWt| * | Molecular Weight Parameter               |        | -0.9206

 Const| * | Equation Constant                        |        | 3.1992

============+============================================+=========+=========

  RESULT  | Biowin3 (Survey Model - Ultimate Biodeg) |        | 3.1448

============+============================================+=========+=========

 

------+-----+--------------------------------------------+---------+---------

 TYPE | NUM |      Biowin4 FRAGMENT DESCRIPTION        | COEFF | VALUE 

------+-----+--------------------------------------------+---------+---------

 Frag | 1 | Linear C4 terminal chain [CCC-CH3]      | 0.2691 | 0.2691

 Frag | 4 | Aliphatic alcohol [-OH]                 | 0.1294 | 0.5178

 Frag | 1 | Ester  [-C(=O)-O-C]                     | 0.2290 | 0.2290

 Frag | 1 | Carbon with 4 single bonds & no hydrogens | -0.1534 | -0.1534

 MolWt| * | Molecular Weight Parameter               |        | -0.6011

 Const| * | Equation Constant                        |        | 3.8477

============+============================================+=========+=========

  RESULT  |  Biowin4 (Survey Model - Primary Biodeg) |        | 4.1091

============+============================================+=========+=========

 

 Result Classification:  5.00 -> hours    4.00 -> days   3.00 -> weeks

 (Primary & Ultimate)   2.00 -> months   1.00 -> longer

 

------+-----+--------------------------------------------+---------+---------

 TYPE | NUM |      Biowin5 FRAGMENT DESCRIPTION        | COEFF | VALUE 

------+-----+--------------------------------------------+---------+---------

 Frag | 4 | Aliphatic alcohol [-OH]                 | 0.1611 | 0.6446

 Frag | 1 | Ester  [-C(=O)-O-C]                     | 0.3437 | 0.3437

 Frag | 1 | Carbon with 4 single bonds & no hydrogens | 0.0676 | 0.0676

 Frag | 1 | Methyl [-CH3]                           | 0.0004 | 0.0004

 Frag | 17 | -CH2- [linear]                          | 0.0494 | 0.8401

 Frag | 1 | -CH-  [linear]                          | -0.0507 | -0.0507

 Frag | 2 | -C=CH [alkenyl hydrogen]                | 0.0062 | 0.0124

 MolWt| * | Molecular Weight Parameter               |        | -1.2394

 Const| * | Equation Constant                        |        | 0.7121

============+============================================+=========+=========

  RESULT  | Biowin5 (MITI Linear Biodeg Probability) |        | 1.3308

============+============================================+=========+=========

 

------+-----+--------------------------------------------+---------+---------

 TYPE | NUM |      Biowin6 FRAGMENT DESCRIPTION        | COEFF | VALUE 

------+-----+--------------------------------------------+---------+---------

 Frag | 4 | Aliphatic alcohol [-OH]                 | 1.0041 | 4.0166

 Frag | 1 | Ester  [-C(=O)-O-C]                     | 2.4462 | 2.4462

 Frag | 1 | Carbon with 4 single bonds & no hydrogens | 0.3990 | 0.3990

 Frag | 1 | Methyl [-CH3]                           | 0.0194 | 0.0194

 Frag | 17 | -CH2- [linear]                          | 0.4295 | 7.3014

 Frag | 1 | -CH-  [linear]                          | -0.0998 | -0.0998

 Frag | 2 | -C=CH [alkenyl hydrogen]                | 0.0285 | 0.0570

 MolWt| * | Molecular Weight Parameter               |        |-12.0268

============+============================================+=========+=========

  RESULT  |Biowin6 (MITI Non-Linear Biodeg Probability)|        | 0.9904

============+============================================+=========+=========

 

 A Probability Greater Than or Equal to 0.5 indicates --> Readily Degradable

 A Probability Less Than 0.5 indicates --> NOT Readily Degradable

 

 

------+-----+--------------------------------------------+---------+---------

 TYPE | NUM |      Biowin7 FRAGMENT DESCRIPTION        | COEFF | VALUE 

------+-----+--------------------------------------------+---------+---------

 Frag | 1 | Linear C4 terminal chain [CCC-CH3]      | -0.3177 | -0.3177

 Frag | 4 | Aliphatic alcohol [-OH]                 | 0.1328 | 0.5311

 Frag | 1 | Ester  [-C(=O)-O-C]                     | 0.1719 | 0.1719

 Frag | 1 | Carbon with 4 single bonds & no hydrogens | -0.3342 | -0.3342

 Frag | 1 | Methyl [-CH3]                           | -0.0796 | -0.0796

 Frag | 17 | -CH2- [linear]                          | 0.0260 | 0.4418

 Frag | 1 | -CH-  [linear]                          | -0.1659 | -0.1659

 Frag | 2 | -C=CH [alkenyl hydrogen]                | -0.0735 | -0.1470

 Const| * | Equation Constant                        |        | 0.8361

============+============================================+=========+=========

  RESULT  |  Biowin7 (Anaerobic Linear Biodeg Prob)  |        | 0.9364

============+============================================+=========+=========

 

 A Probability Greater Than or Equal to 0.5 indicates --> Biodegrades Fast

 A Probability Less Than 0.5 indicates --> Does NOT Biodegrade Fast

 

Ready Biodegradability Prediction: (YES or NO)

----------------------------------------------

 Criteria for the YES or NO prediction: If the Biowin3 (ultimate survey

 model) result is "weeks" or faster (i.e. "days", "days to weeks", or

 "weeks" AND the Biowin5 (MITI linear model) probability is >= 0.5, then

 the prediction is YES (readily biodegradable). If this condition is not

 satisfied, the prediction is NO (not readily biodegradable). This method

 is based on application of Bayesian analysis to ready biodegradation data

 (see Help). Biowin5 and 6 also predict ready biodegradability, but for

 degradation in the OECD301C test only; using data from the Chemicals

 Evaluation and Research Institute Japan (CERIJ) database.

Validity criteria fulfilled:
yes
Remarks:
Validated QSAR, part of the OECD (Q)SAR Toolbox
Interpretation of results:
readily biodegradable
Conclusions:
The BIOWIN v4.10 model predicted that the substance is readily biodegradable. The BIOWIN1 value = 1.2828 and the BIOWIN2 value = 0.9969 were both greater than 0.5 and indicated fast biodegradation. The BIOWIN3 value = 3.1448 indicated a timeframe of weeks to ultimate biodegradation, and the BIOWIN4 value of 4.1091 indicated a timeframe of days to primary degradation. The BIOWIN5 value = 1.3308 and the BIOWIN6 value = 0.9904 were both greater than 0.5, and both indicated the substance is readily biodegradable. The BIOWIN7 value of 0.9364 was greater than 0.5, and indicated that it biodegrades fast under anaerobic conditions.

Description of key information

The biodegradability of the substance in water was determined through a weight-of-evidence evaluation using two studies. An analogue substance exhibited ready biodegradability in a CO2 evolution test (i.e., 69% degradation in 29 days, not meeting the 10-day window); the 10-day window does not apply to multi-constituent and UVCB substances and the test substance (as a UVCB) may thus be considered readily biodegradable.  In addition, a validated QSAR model (EPI Suite BIOWIN 4.10) predicted that the substance itself is readily biodegradable, based on two modules within the model: BIOWIN 3, which predicted ultimate degradation of the substance in the timeframe of “weeks”, and BIOWIN 5, which predicted that the substance “biodegrades fast”.  Four additional modules within the model (BIOWIN 1, BIOWIN 2, BIOWIN 6 and BIOWIN 7) predicted that the substance “biodegrades fast”; one module (BIOWIN 4) predicts that primary degradation occurs within the timeframe of “days”.  In summary, the QSAR prediction indicates that the substance does not contain any structural components that are refractory to rapid environmental degradation; this prediction is verified by the laboratory test on the analogue substance. 

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information